That's certainly ominous, but it sounds like fans will not be getting any more information than that. The New York Times approached Showrunner Sarah Treem, and she released the following statement:

We can’t speak for Ruth, but heading into Season 4, everyone agreed the character’s story had run its course.

Ultimately, it felt like the most powerful creative decision would be to end Alison’s arc at the moment when she had finally achieved self-empowerment.

The impact of her loss will be felt as the series concludes next season. We thank the many fans who embraced the character of Alison and especially thank Ruth for her indelible work over the past four seasons.

This is the same statement that was released after Wilson's final episode of the series aired earlier this month.

Alison seemingly got her happy ending in one, with her and Ben working out their issues. The other found Ben flip out when Alison threatened to tell his wife everything if he didn't leave her alone.

He subsequently attacked her, before throwing her body into the ocean. There's no telling whether either of these scenarios were the correct chain of events, or if her demise was a mixture of both or something else entirely.